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Previous issue date: 2014-09-15 / Neste trabalho foram desenvolvidos estudos sint?ticos e te?ricos para clerodanos
bioativos obtidos de uma das plantas medicinais mais representativas da regi?o
Amaz?nica do Brasil, Croton cajucara Benth. Especificamente, utilizou-se como
mol?cula alvo o biocomposto majorit?rio isolado das cascas do caule deste Croton, o
diterpen?ide 19-nor-clerodano trans-desidrocrotonina (t-DCTN). Derivados semisint?ticos
foram obtidos de t-DCTN utilizando-se os seguintes procedimentos sint?ticos:
1) redu??o catal?tica com H2, 2) redu??o com NaBH4 e 3) redu??o estereosseletiva com
NaBH4/CeCl3). Os derivados semi-sint?ticos do tipo 19-nor-furano-clerodanos
alco?licos foram denominados de t-CTN, t-CTN-??OL, t-CTN-??OL, t-DCTN-??OL
e t-DCTN-??OL, tendo sido caracterizados por RMN. Os ?lcoois clerodanos derivados
t-CTN-??OL e t-CTN-??OL foram obtidos a partir do derivado semi-sint?tico t-CTN,
que tamb?m pode ser isolado das cascas do caule de C. cajucara.
Uma metodologia te?rica (DFT/B3LYP) envolvendo a previs?o de propriedades
geom?tricas e magn?ticas como ?ngulos e dist?ncias de liga??es bem como
deslocamento qu?mico e constante de acoplamento, foi desenvolvida para a mol?cula
alvo t-DCTN em que foram correlacionados dados te?ricos de RMN e estruturais, tendo
sido obtidas correla??o satisfat?rias com dados experimentais de RMN (com
coeficientes de correla??o variando entre 0,97 e 0,99) e de difra??o de Raios-X. Esta
metodologia te?rica foi validada para todos os derivados semi-sint?ticos apresentados
neste trabalho. Em adi??o, informa??es topol?gicas obtidas com o aux?lio da Teoria
Qu?ntica de ?tomos em Mol?culas (QTAIM) evidenciaram a presen?a de intera??es
estabilizantes intramoleculares do tipo H-H e (C)O--H(C) em t-DCTN e t-CTN,
contribuindo para o entendimento da diferente reatividade destes clerodanos na presen?a
de NaBH4. / In this work it were developed synthetic and theoretical studies for clerodane-type
diterpenes obtained from Croton cajucara Benth which represents one of the most
important medicinal plant of the Brazil amazon region. Specifically, the majoritary
biocompound 19-nor-clerodane trans-dehydrocrotonin (t-DCTN) isolated from the bark
of this Croton, was used as target molecule. Semi-synthetic derivatives were obtained
from t-DCTN by using the followed synthetic procedures: 1) catalytic reduction with
H2, 2) reduction using NaBH4 and 3) reduction using NaBH4/CeCl3. The semi-synthetic
19-nor-furan-clerodane alcohol-type derivatives were denominated such as t-CTN, tCTN-??OL,
t-CTN-??OL, t-DCTN-??OL, t-DCTN-??OL, being all of them
characterized by NMR. The furan-clerodane alcohol derivatives t-CTN-??OL and tCTN-??OL
were obtained form the semi-synthetic t-CTN, which can be isolated from
the bark of C. cajucara.
A theoretical protocol (DFT/B3LYP) involving the prevision of geometric and magnetic
properties such as bond length and angles, as well as chemical shifts and coupling
constants, were developed for the target t-DCTN in which was correlated NMR
theoretical data with structural data, with satisfactory correlation with NMR
experimental data (coefficients ranging from 0.97 and 0.99) and X-ray diffraction data.
This theoretical methodology was also validated for all semi-synthetic derivatives
described in this work. In addition, topological data from the Quantum Theory of Atoms
in Molecules (QTAIM) showed the presence of H-H and (C)O--H(C) intramolecular
stabilized interactions types for t-DCTN e t-CTN, contributing to the understanding of
the different reactivity of this clerodanes in the presence of NaBH4.
| Identifer | oai:union.ndltd.org:IBICT/oai:repositorio.ufrn.br:123456789/19755 |
| Date | 15 September 2014 |
| Creators | Soares, Breno Almeida |
| Contributors | 37320165449, http://lattes.cnpq.br/5360188002708095, Menezes, Fabricio Gava, 03114939988, http://lattes.cnpq.br/2848745987784319, Souza, Pierre Andr? de, 81094361968, http://lattes.cnpq.br/3428061204977867, Castro, Rosane Nora, 95806733734, http://lattes.cnpq.br/5479814788308057, Firme, Caio Lima, Maciel, Maria Aparecida Medeiros |
| Publisher | Universidade Federal do Rio Grande do Norte, PROGRAMA DE P?S-GRADUA??O EM QU?MICA, UFRN, Brasil |
| Source Sets | IBICT Brazilian ETDs |
| Language | Portuguese |
| Detected Language | English |
| Type | info:eu-repo/semantics/publishedVersion, info:eu-repo/semantics/doctoralThesis |
| Source | reponame:Repositório Institucional da UFRN, instname:Universidade Federal do Rio Grande do Norte, instacron:UFRN |
| Rights | info:eu-repo/semantics/openAccess |
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